1. Field of the Invention
This invention relates to an external data communication arrangement for a programmable AC electric energy meter having a sealed enclosure and more particularly to such an arrangement including a transparent communications window portion of the enclosure for receiving and transmitting coded radiations into and from a radiation sensitive external data interface.
2. Description of the Prior Art
Induction watthour meters including electromechanical meter movements are almost universally used for use as electric energy billing meters. The use of such induction watthour meters are well established because of their high degree of accuracy, mass production by economical manufacturing techniques, high reliability during many years of service under widely varying ambient operating conditions, and simple and easy installation. Presently, solid state electronic circuits are increasingly being used since the size and cost of complex electronic circuits have been substantially reduced by the use of large-scale integration circuit techniques and such circuits have been found to have increasing reliability and extended ambient operating ranges of operation. Accordingly, it is sometimes possible to utilize electronic circuits to replace all or portions of the prior electromechanical meter movement of induction watthour meters. The use of such circuits provides the advantages of larger varieties of different modes of measuring operations, including measurements of different parameters of electric energy consumption and the ability to separately perform such measurements at different time of usage periods corresponding to the on and off peak load conditions of an electric utility distribution system supplying the electric energy being measured.
In U.S. Pat. No. 4,077,061, issued Feb. 28, 1978, for A Digitally Processing And Calculating AC Electric Energy Measuring System, and assigned to the assignee of this invention, an all solid state electronic metering circuit is described and claimed utilizing a microprocessor forming a digital sequence controller and calculator subsystem. A program read-only memory (ROM) and a data random access memory (RAM) are disclosed for use with the microprocessor based system. The metering system is an integral package intended to receive certain analog voltage and current signals to be measured and to also receive integral timing pulses so as to produce a number of different measuring output signals and to also provide a visual readout display representing such signals. Manual switch inputs are also provided for the selection of one of the different parameters being made for visual display. The aforementioned system does not disclose a method of transmitting and receiving program data information. As is known in the use of such programmable processors, the ability to change or add program data information is sometimes found desirable. The program data must be supplied through an external data interface not disclosed in the aforementioned patent.
Since billing meters incorporating solid state electronic circuits are required to perform in the same ambient environments as are the prior all-electromechanical types of induction meters and to be attachable at existing meter sockets, the same general type of meter enclosures are required. These enclosures typically include a base and a transparent cup-shaped cover attached to the base. The cover is usually made of a transparent glass or impact resistant transparent plastic material to protect the metering system from environmental conditions and to protect the system from unauthorized access thereto. When an electronic programmable electric energy measuring system is housed in such an enclosure, it is desirable to maintain the protective and securing features of the enclosure while providing external connections thereto when required. In U.S. Pat. No. 4,110,814, issued Aug. 29, 1978, and assigned to the assignee of this invention, a watthour meter enclosure is disclosed wherein an opening is provided in the side of the enclosure to form a passage for wire conductors connected to an electronic meter encoding circuit for remote meter reading systems.
In U.S. Pat. No. 4,050,020, A Multiple Rate Electrical Energy Metering System is disclosed having a programmable digital logic control circuit. The system further includes a circulating memory incorporating a programmable timing circuit arrangement. A socket type connector is disclosed for receiving a plug associated with a portable programmer and tester unit used to transmit data to the memory portion of the system. The programmer plug is insertable through the face of the cup-shaped meter cover and a removable lock or seal is required to prevent unauthorized access to the socket connector.
While the aforementioned physical connections through the meter enclosure are often quite satisfactory, it is sometimes desirable to further protect the metering circuits by avoiding the necessity of providing openings through the enclosure.
An optical reader for externally programming a microprocessor is disclosed in U.S. Pat. No. 4,056,711, wherein optically coded patterns of reflecting and non-reflecting indicia are positioned over optical transducers of the reader. Coded impulses from the transducers produce address and data to random access memories of the programming system. In U.S. Pat. No. 3,789,193, machine readable indications are sensed by an optical reader which transmits corresponding data pulses to a computer controller. In U.S. Pat. No. 4,063,083, an optical data link is established between interfacing assemblies by selectively positioning apertures of matrix boards in a fixed optical light path. Optical data communication is thereby provided between spaced locations.
Accordingly, it is desired to transmit and receive data to and from an electric energy meter having a programmable measuring system including an associated read-write programmable memory housed in a weatherproof and tamper resistant enclosure without alteration or interference with the integrity of such an enclosures. It is further desirable to establish radiation responsive type data link with such measuring systems through a transparent communications window portion of a meter enclosure. The radiation data link is desired to be provided by a compact, reliable, and easily assembled arrangement that is simply used and protects against both outdoor environmental conditions and tampering of electric energy measuring systems.